大约有 40,000 项符合查询结果（耗时：0.1981秒） [XML]
differentiate null=True, blank=True in django
When we add a database field in django we generally write:
18 Answers
18
...
advantage of tap method in ruby
...= User.new
user.username = "foobar"
user.save!
they would have to follow all the three lines and then recognize that it is just creating an instance named user.
If it were:
user = User.new.tap do |u|
u.username = "foobar"
u.save!
end
then that would be immediately clear. A reader would not...
source of historical stock data [closed]
I'm trying to make a stock market simulator (perhaps eventually growing into a predicting AI), but I'm having trouble finding data to use. I'm looking for a (hopefully free) source of historical stock market data.
...
Best practice? - Array/Dictionary as a Core Data Entity Attribute [closed]
...m the data store (if it's an SQLite data store) just to read or modify a small part of the collection.
The alternative is to use Core Data to-many relationships to model the semantics of the array or dictionary collection. Arrays are easier, so lets start with that. Core Data to-many relationships ...
Mercurial — revert back to old version and continue from there
I'm using Mercurial locally for a project (it's the only repo there's no pushing/pulling to/from anywhere else).
7 Answers
...
A list of indices in MongoDB?
...
If you want to list all indexes:
db.getCollectionNames().forEach(function(collection) {
indexes = db.getCollection(collection).getIndexes();
print("Indexes for " + collection + ":");
printjson(indexes);
});
...
Margin while printing html page
... inside the printable area.
You should also be aware that IE7++ automatically adjusts the size to best fit, and causes everything to be wrong even if you use cm or mm. To override this behaviour, the user must select 'Print preview' and then set the print size to 100% (default is Shrink To Fit).
...
Play/pause HTML 5 video using JQuery
...jQuery function but a function of the DOM element. You therefore need to call it upon the DOM element. You give an example of how to do this with the native DOM functions. The jQuery equivalent -- if you wanted to do this to fit in with an existing jQuery selection -- would be $('#videoId').get(0...
Find out if ListView is scrolled to the bottom?
...r_list_id:
// Make your calculation stuff here. You have all your
// needed info from the parameters of this function.
// Sample calculation to determine if the last
// item is fully visible.
final int lastItem = firstVisibleItem + ...
Custom CSS Scrollbar for Firefox
...ording to the spec. Both thin and a specific length may not do anything on all platforms, and what exactly it does is platform-specific. In particular, Firefox doesn't appear to be currently support a specific length value (this comment on their bug tracker seems to confirm this). The thin keywork d...